The present invention relates to a hydraulic pressure booster system, in which a hydraulic pressure booster equipment such as brake booster boosts the input to the predetermined value and outputs it by the pressurized operating fluid from hydraulic pressure generating means.
The hydraulic pressure booster system is used in various equipment and devices such as brake booster system in brake unit of automobile or clutch booster system in power transmission equipment, and it provides big operating force by small actuating force.
In the hydraulic pressure booster system of conventional type, hydraulic pressure generating means is provided for generating hydraulic pressure because hydraulic pressure is utilized, and a pump consisting of piston pump is normally used as such hydraulic pressure generating means.
However, in case such piston pump is used, pulsation occurs in the hydraulic pressure circuit by reciprocal movement of the piston, and this pulsation is transmitted to the hydraulic pressure booster equipment through the hydraulic pressure circuit. For this reason, the noise caused by pump pulsation is generated in the vehicle through the hydraulic pressure booster equipment. Also, because of such pump pulsation, stable operation of the hydraulic pressure booster equipment is hindered.
To solve the problem, it is proposed that an accumulator to absorb this pulsation is provided on the supply passage to feed the operating fluid. By such accumulator, pump pulsation can be absorbed to some extent.
However, it is difficult by this accumulator for absorbing pulsation in some cases to absorb the pulsation efficiently and adequately, and the transmission of the pulsation to the hydraulic pressure booster equipment cannot be prevented completely.
Even in such case, it is desirable that pulsation can be absorbed as much as possible. To cope with such demand, study has been performed in various ways, and it has been found that, if long flexible hose is furnished before and after the accumulator, the pulsation can be efficiently absorbed even when it is difficult to absorb the pulsation by accumulator only. In such case, in order to perfectly obtain the pulsation absorbing effect by flexible hose, it is necessary to sufficiently extend the length of the hose.
Incidentally, the hydraulic pressure booster equipment such as hydraulic brake booster or hydraulic clutch booster equipment must be designed in compact form to suit the place or the space where it is furnished. Therefore, the length of the flexible hose as described above must also be limited to such length as to match the layout of the system.
Thus, the demands must be fulfilled, on the one hand to extend the length of the hose as long as possible in order to obtain the better pulsation absorbing effect, and on the other hand, to shorten the length of the hose to meet the requirements limited by the layout of the system.